Abstract: A high temperature superconducting, HTS, current lead comprising an HTS cable including a plurality of HTS tapes, a braided sleeve around the HTS cable, and a stabiliser material impregnating the HTS cable and the braided sleeve, the stabiliser material having a melting point above 290K and below a thermal degradation temperature of the HTS tapes.

Abstract: A method of manufacturing a High Temperature Superconductor, HTS, field coil from one or more HTS tapes. Each HTS tape comprises an HTS material layer. The method comprises: winding the one or more HTS tapes about an axis to form a field coil comprising windings of HTS tape; and removing material from an axial edge of the one or more of the HTS tapes around at least a part of one or more of the windings to reduce the extent of the one or more HTS tapes along the axis of the field coil.

Abstract: A high temperature superconducting, HTS, field coil. The HTS field coil comprises a plurality of turns comprising HTS material and metallic stabilizer; and a partially insulating layer separating the turns, such that current can be shared between turns via the partially insulating layer. The partially insulating layer comprises an insulating region, and a plurality of electrically conductive paths through the insulating region, wherein current can be shared between the turns via the electrically conductive paths. Each electrically conductive path comprises an HTS bridge comprising HTS material, wherein the HTS bridge is in series with normally conducting material of the electrically conductive path.

Abstract: A high temperature superconducting, HTS, magnet system. The HTS magnet system comprises an HTS field coil, a temperature control system, a power supply, and a controller. The HTS field coil comprises a plurality of turns comprising HTS material; and a resistive material electrically connecting the turns, such that current can be shared radially between turns via the resistive material. The temperature control system is configured to control the temperature of the coil, the temperature control system comprising at least a cryogenic cool system configured to keep the coil below a self-field critical temperature of the HTS material. The power supply is configured to supply current to the HTS field coil. The controller is configured to cause the power supply to provide a current greater than a critical current of all of the HTS material.

Abstract: According to a first aspect, there is provide an HTS current lead. The HTS current lead comprises an HTS cable comprising a plurality of HTS tapes; a braided sleeve around the HTS cable; and a stabiliser material impregnating the HTS cable and the braided sleeve. The stabiliser material has a melting point above a critical temperature of the HTS tapes and below a thermal degradation temperature of the HTS tapes.

Abstract: A High Temperature Superconductor, HTS, magnet comprising a coil formed of nested concentric windings. Each winding comprises HTS material. The HTS magnet further comprises a conductor element comprising an electrical contact surface through which to supply electric current to a portion of at least one of the windings. The surface provides electrical contact between the conductor element and an axial edge of the coil substantially around the path of the at least one of the windings.

Abstract: A high temperature superconducting, HTS, field coil. The HTS field coil has a plurality of turns and a semiconductor, arranged such that current can be shared between the turns via the semiconductor.

Abstract: A cable for carrying electrical current in a coil of a magnet. The cable comprises a stack of tape assemblies. Each tape assembly has a length and a width, such that the length is much larger than the width, and each tape assembly comprises an HTS layer of anisotropic high temperature superconductor, HTS material, wherein a c-axis of the HTS layer is at a non-zero angle to a vector perpendicular to the plane of the HTS layer. The tape assemblies are stacked as a series of pairs, each pair comprising first and second HTS tape assemblies and a copper layer therebetween. The tape assemblies in each pair are arranged such that the c-axis of the HTS layer of the first HTS tape assembly of each pair have reflective symmetry to the c-axis of the HTS layer of the second HTS tape assembly of each pair about a plane which is parallel to and equidistant from each HTS layer.

Abstract: A monitoring device for use in a cryogenic system. The monitoring device comprises first and second conducting elements and a current detector. The first conducting element comprises high temperature superconducting, HTS, material and is configured for connection to a current source and insertion into the cryogenic system. The second conducting element comprises HTS material and is connected in parallel to the first conducting element by first and second joints. The current detector is configured to detect a current in the second conducting element. When the HTS material in each of the first and second conducting elements is in a superconducting state, the resistance, RT, of the first conducting element between the first and second joints, is less than the sum, RB, of the resistance of the second conducting element between the first and second joints and the resistances of the first and second joints.

Abstract: A high temperature superconductor, HTS, tape (100) for detecting a quench in a superconducting magnet. The HTS tape comprises an HTS layer (101) of HTS material supported by a substrate (102). The HTS layer is divided into a plurality of strips (104,105,107). The strips are connected (106) in series along an open path.

Abstract: A high temperature superconducting, HTS, field coil. The HTS field coil comprises a plurality of turns and a partially insulating layer. The plurality of turns comprises HTS material and metallic stabilizer. The partially insulating layer separates the turns, such that current can be shared between turns via the partially insulating layer. The partially insulating layer comprises an electrically conducting layer, and first and second insulating layers. The electrically conducting layer is coated on one side with the first insulating layer and on the other side with the second insulating layer. Each insulating layer has one or more windows through which electrical contact can be made between the turns and the electrically conducting layer. The windows in the first insulating layer are offset in the plane of the electrically conducting strip from the windows in the second insulating layer.

Abstract: There is disclosed a toroidal field coil for use in a spherical tokamak. The toroidal field coil comprises a central column and a plurality of return limbs. The central column comprises a plurality of exfoliated HTS tapes, and the return limbs comprise a plurality of substrated HTS tapes. Each exfoliated HTS tape comprises a ReBCO layer bonded to respective metal interface layers on each side of the ReBCO layer, each metal interface layer being bonded to a metal stabiliser layer. Each substrated HTS tape comprises a ReBCO layer bonded on one side to a metal interface layer and on the other side to an oxide buffer stack, the metal interface layer being bonded to a metal stabiliser layer and the oxide buffer stack being bonded to a substrate.

Abstract: A monitoring device for use in a cryogenic system. The monitoring device comprises first (201) and second (202) conducting elements and a current detector (205). The first conducting element comprises high temperature superconducting, HTS, material and is configured for connection to a current source (203) and insertion into the cryogenic system. The second conducting element comprises HTS material and is connected in parallel to the first conducting element by first and second joints (204). The current detector is configured to detect a current in the second conducting element. When the HTS material in each of the first and second conducting elements is in a superconducting state, the resistance, RT, of the first conducting element between the first and second joints, is less than the sum, RB, of the resistance of the second conducting element between the first and second joints and the resistances of the first and second joints, RT<RB.

Abstract: A high temperature superconducting, HTS, field coil. The HTS field coil comprises a plurality of turns and a partially insulating layer. The plurality of turns comprises HTS material and metallic stabilizer. The partially insulating layer separates the turns, such that current can be shared between turns via the partially insulating layer. The partially insulating layer comprises an electrically conducting layer, and first and second insulating layers. The electrically conducting layer is coated on one side with the first insulating layer and on the other side with the second insulating layer. Each insulating layer has one or more windows through which electrical contact can be made between the turns and the electrically conducting layer. The windows in the first insulating layer are offset in the plane of the electrically conducting strip from the windows in the second insulating layer.

Abstract: According to a first aspect of the present invention, there is provided a method of forming a superconducting joint between ReBCO tapes. Two or more ReBCO tapes are provided, each having an exposed ReBCO region. A bridge is provided, comprising an exposed ReBCO layer and an oxygen-permeable backing on the exposed ReBCO layer. Each exposed ReBCO region is bonded to the exposed ReBCO layer of the bridge by heating to a first temperature (T1) in an environment where the partial pressure of oxygen is sufficiently low that the melting point of the ReBCO (TR) is less than the melting point of silver (TAg), the temperature (T1) being between the melting point of the ReBCO (TR) and the melting point of silver (TAg), (TR<T1<TAg). The resulting joint is annealed at a second temperature (T2) which is less than the melting point of ReBCO (TR) (T2<TR), for a time (t), in an environment where the partial pressure of oxygen is sufficient to reoxygenate the ReBCO at the second temperature (T2).

Abstract: There is disclosed a toroidal field coil for use in a spherical tokamak. The toroidal field coil comprises a central column and a plurality of return limbs. The central column comprises a plurality of exfoliated HTS tapes, and the return limbs comprise a plurality of substrated HTS tapes. Each exfoliated HTS tape comprises a ReBCO layer bonded to respective metal interface layers on each side of the ReBCO layer, each metal interface layer being bonded to a metal stabiliser layer. Each substrated HTS tape comprises a ReBCO layer bonded on one side to a metal interface layer and on the other side to an oxide buffer stack, the metal interface layer being bonded to a metal stabiliser layer and the oxide buffer stack being bonded to a substrate.

Abstract: According to a first aspect of the present invention, there is provided a method of forming a superconducting joint between ReBCO tapes. Two or more ReBCO tapes are provided, each having an exposed ReBCO region. A bridge is provided, comprising an exposed ReBCO layer and an oxygen-permeable backing on the exposed ReBCO layer. Each exposed ReBCO region is bonded to the exposed ReBCO layer of the bridge by heating to a first temperature (T1) in an environment where the partial pressure of oxygen is sufficiently low that the melting point of the ReBCO (TR) is less than the melting point of silver (TAg), the temperature (T1) being between the melting point of the ReBCO (TR) and the melting point of silver (TAg), (TR<T1<TAg). The resulting joint is annealed at a second temperature (T2) which is less than the melting point of ReBCO (TR) (T2<TR), for a time (t), in an environment where the partial pressure of oxygen is sufficient to reoxygenate the ReBCO at the second temperature (T2).

Abstract: A high temperature superconductor, HTS, tape (100) for detecting a quench in a superconducting magnet. The HTS tape comprises an HTS layer (101) of HTS material supported by a substrate (102). The HTS layer is divided into a plurality of strips (104,105,107). The strips are connected (106) in series along an open path.